A hexagonal shape surface plasmon photonic crystal fiber (PCF) biosensor is reported and studied numerically. The proposed design has three identical cores along the y-axis filled with liquid (analyte). Additionally, the central core is coated by a gold layer to facilitate the coupling among the plasmonic modes and the core fundamental modes. A full vectorial finite element method is used to analyze the proposed sensor with a perfectly matched layer boundary condition. Further, the particle swarm optimization (PSO) technique is used to optimize and improve the sensitivity of the presented sensor as well as reduce the sensor’s size. Through the optimization process, the diameters of the three cores, and the thicknesses of the gold layer are fluctuated. For a wavelength range 1.46-1.47, the sensitivity of the proposed sensor is 4000 nm/RIU.
In this paper, we study the use of Titanium Nitride (TiN) as a new alternative plasmonic material to achieve a highly sensitive surface plasmon resonance (SPR) photonic crystal fiber (PCF) biosensor. The TiN has unique properties that make it an ideal material for nanofabrication, where TiN is highly stable, highly conductive, and corrosion resistant. Full vectorial finite element method is used with perfectly matched layer (PML) as boundary conditions to analyze the suggested biosensor. By analyzing the geometrical parameters of the proposed biosensor, a refractive index sensitivity of 7700 nm/RIU and 3600 nm/RIU are obtained for quasi-transverse electric (TE) and quasi transverse magnetic (TM) modes, respectively. The reported biosensor has a high linearity for detecting an unknown analyte refractive index ranging from 1.32 to 1.34. Further, fabrication of the proposed biosensor could be done using standard PCF fabrication current technologies.
A modified nanocone nanowire (NW) is proposed and analyzed for solar cell applications. The suggested NW consists of conical and truncated conical units. The geometrical parameters are studied by using 3D finite difference time domain (FDTD) method to achieve broadband absorption through the reported design and maximize its ultimate efficiency. The analyzed parameters are absorption spectra, ultimate efficiency and short circuit current density. The numerical results prove that the proposed structure is superior compared to cone, truncated cone and cylindrical nanowires (NWs). The reported design achieves an ultimate efficiency of 44.21% with an enhancement of 40.66% relative to the conventional conical NWs. Further, short circuit current density of 36.17 mA/cm2 is achieved by the suggested NW. The modified nanocone has advantages of broadband absorption enhancement, low cost and fabrication feasibility.
In this paper, new design of Yagi-Uda nano-antenna (NA) based on ellipsoid shape is introduced and numerically analyzed using 3-D finite difference time domain method (3-D FDTD) via Lumerical software package. The NA parameters are optimized using the particle swarm optimization (PSO) algorithm to achieve high directivity at a wavelength of 500 nm for wireless point-to-point applications. To illustrate the performance of the proposed antenna, different radiation parameters such as radiation pattern, directivity, and radiation efficiency have been studied. The optimized ellipsoid nano-antenna shows a directivity of 22.36 which is enhanced by 86.3 % relative to the conventional spherical counterpart. Moreover, the fabrication tolerance of the reported design is studied to ensure the accuracy of the introduced NA parameters to the fabrications errors.
In this study, the absorption capabilities of a plasmonic funnel-shaped silicon nanowire (SiNW) solar cell is introduced and analyzed by using 3D finite difference time domain method (FDTD). The reported NW design has titanium nitride (TiN) core as an alternative plasmonic material. The different geometrical parameters of the reported design are studied to maximize the absorption and hence the ultimate efficiency. An ultimate efficiency and short-circuit current density Jsc of 48.3% and 38.98 mA/cm2, respectively are obtained which are greater than the conventional Si-Funnel counterpart by 46.36%. The enhancement of the light absorption is attributed to the combination between different types of optical modes and plasmonics modes of the funnel-shaped NW and the TiN, respectively.
A novel design of multiplexer-demultiplexer (MUX-DEMUX) based on channel waveguide on silicon dioxide (SiO2) is introduced and analyzed. The suggested structure consists of two neighboring channels infiltrated with nematic liquid crystal (NLC) material of type E7. The two channels are etched in the SiO2 substrate. The electro-optic effect of the NLC is used to control the waveguide propagation condition using an external electric field. Additionally, a plasmonic wire is inserted between the two waveguides to enhance the suggested MUX-DEMUX in terms of compactness. The modal analysis of the y-polarized modes supported by the NLC MUX-DEMUX is carried out using full-vectorial finitedifference method (FVFDM). Further, the propagation characteristics through the reported design are obtained using full vectorial finite difference beam propagation method (FVFD-BPM). The design parameters of the NLC MUX-DEMUX have been studied to obtain an efficient waveguide coupling with a short device length. Moreover, the NLC MUXDEMUX has a compact device length of 1296 μm. The numerical results reveal that the reported MUX-DEMUX has a small insertion loss of 8x10-6 dB with a good crosstalk better than -37 dB and -30 dB at the studied wavelengths of 1.3 μm and 1.55 μm, respectively. To the best of the authors’ knowledge, it is the first time to introduce a MUX-DEMUX based on channel on SiO2 platform with a simple design and broadband operation.
In order to detect DNA hybridization with label free and high sensitivity, a hybrid alternative plasmonic slot waveguide (HAPSW) biosensor based on silicon-on-insulator (SOI) is proposed and analyzed. The reported design increases the light interaction with the sensing region by using a slot-waveguide along with titanium nitride as an alternative plasmonic material. The suggested biosensor can detect the slightest change in the analyte refractive index with high sensitivity due to an ultra-high optical confinement in the low-index regions caused by the high index contrast and plasmonic enhancement. The effective index, normalized power confinement, and sensitivity are analyzed for the detection of the DNA hybridization. The simulation results are obtained using full vectorial finite element method (FVFEM). The suggested biosensor has high sensitivity of 1190 nm/RIU (refractive index unit) for DNA hybridization detection, which is very high relative to those reported in the literature to the best of our knowledge.
Improving solar cell efficiency is a critical research topic. Nowadays, light trapping techniques are a promising way to enhance solar cell performance. A modified nanocone nanowire (NW) is proposed and analyzed for solar cell applications. The suggested NW consists of conical and truncated conical units. The geometrical parameters are studied using a three-dimensional (3-D) finite difference time-domain (FDTD) method to achieve broadband absorption through the reported design and maximize its ultimate efficiency. The analyzed parameters are absorption spectra, ultimate efficiency, and short circuit current density. The numerical results prove that the proposed structure is superior compared with cone, truncated cone, and cylindrical NWs. The reported design achieves an ultimate efficiency of 44.21% with substrate and back reflector. Further, short circuit current density of 36.17 mA / cm2 is achieved by the suggested NW. The electrical performance analysis of the proposed structure including doping concentration, junction thickness, and Shockley–Read–Hall recombination is also investigated. The electrical simulations show that a power conversion efficiency of 17.21% can be achieved using the proposed NW. The modified nanocone has advantages of broadband absorption enhancement, low cost, and fabrication feasibility.
A design of hydrogenated amorphous silicon (a-Si:H) solar cell (SC) based on one-dimensional subwavelength grating with nonuniform distribution is proposed and optimized using modified hybrid gravitational search algorithm and particle swarm optimization (GSA-PSO). The reported structure consists of nine gratings with different widths, positions, and heights that can enhance the light trapping through the SC. The nonuniform grating positions and geometrical parameters of the proposed design are optimized in terms of absorption, ultimate efficiency, and short circuit current density. The absorption inside the active layer is enhanced by 67.5% over the conventional thin-film SC. Further, the exposed area caused by forward nanotexturing surface is increased. Moreover, the nonuniform grating parameters and distribution support better light absorption than the periodic grating distribution by increasing the optical path length of the incident light through the active layer. Therefore, the suggested SC achieves a broadband absorption improvement. The enhanced absorption in the active layer is reported using three-dimensional finite-difference time-domain method. In addition, the performance of the suggested SC using different active layer materials, i.e., crystalline silicon, a-Si:H, and gallium arsenide is studied. The hydrogenated amorphous silicon-based design shows high ultimate efficiency of 38.73%, short-circuit current density (JSC) of 34.69 mA / cm2, open-circuit voltage of 1.0393 V, and power conversion efficiency of 35.4%. The modified GSA-PSO algorithm shows also high potential for the design and optimization of different types of solar cells.
Silicon nanowires (Si NWs) array have emerged as a promising route on the road to achieve highly efficient solar cells (SCs). The NWs SCs can achieve highly efficient light trapping with reduced cost and material usage. However, it is difficult to fabricate NWs with smoothed surfaces due to the deficiency in the fabrication process. The surface roughness of SCs is an essential parameter of the optoelectronic performance of these devices. In this paper, the effect of surface roughness on the optical and electrical performance of the NW SCs is reported and analyzed. The optical absorption and the generation rates are calculated using 3D finite difference time domain (FDTD) method while the electrical characteristics are calculated using finite element method via Lumerical device software package. In this investigation, short circuit current density, open circuit voltage and power conversion efficiency (PCE) are numerically studied to quantify the electrical performance of the reported structure. The simulation results show that the Si NWs with 10% surface roughness has higher PCE than smoothed Si NWs counterpart by 8.33%. This is due to the multiple scattering between the SiNWs which increases the light absorption and hence the PCE.
In this paper, a highly sensitive surface plasmon photonic crystal fiber (PCF) biosensor is reported and studied to monitor glucose concentration. The suggested design is based on a well-known large mode area (LMA) single mode PCF infiltrated by a plasmonic material. Additionally, an etching process is applied to increase the biosensor sensitivity. The numerical analysis is obtained using a full vectorial finite element method (FVFEM). The suggested biosensor based on a commercial PCF with plasmonic rod achieves sensitivity as high as 7900 nm/RIU with corresponding resolution of 1.26 × 10-5RIU-1. The analysis also reveals that the proposed biosensor has a linear performance which is needed practically. Therefore, the reported biosensor has advantages in terms of fabrication feasibility and high linear sensitivity
The electrical characteristics of funnel-shaped silicon nanowire (SiNW) solar cells are introduced and numerically analyzed. The funnel-shaped NW consists of a cylinder over a conical unit. Its aim is to maximize the optical absorption over a large wavelength range and hence the electrical efficiency by increasing the number of resonance wavelengths or by enlarging the resonance wavelength range. The conical part has different radii in the axial direction, which increases the number of resonance wavelengths. Further, the coupling between the supported modes by the upper cylinder and the lower tapered cone offers multiple optical resonances required for broadband absorption. The optical characteristics and generation rates through the studied design are obtained using 3-D finite difference time domain. However, the electrical properties are calculated using finite element via the Lumerical device software package. In this regard, radial and axial junctions are examined for the suggested design and compared with the conventional cylindrical SiNW counterpart. In this investigation, short circuit current density, open circuit voltage, fill factor, and power conversion efficiency (PCE) are simulated to quantify the optoelectronic performance of the reported design. Furthermore, the effects of the doping concentration and carrier lifetime on the performance of the funnel-shaped design are reported. The proposed SiNWs offer PCE and short circuit density of 12.7% and 27.6 mA/cm2, respectively, for the axial junction. However, the funnel design with core–shell junction shows an efficiency and short-circuit current (Jsc) of 14.13% and 31.94 mA/cm2, respectively. Therefore, the suggested design has higher efficiency than 6.4% and 9.6% of the conventional cylindrical SiNWs according to the axial and core shell junctions, respectively.
An approach to enhance the ultimate efficiency of the silicon nanowires (Si NWs) solar cell is proposed based on a hybrid population-based algorithm. The suggested technique integrates the ability of exploration in a gravitational search algorithm (GSA) with the exploitation capability of particle swarm optimization (PSO) to synthesize both algorithms’ strengths. The hybrid GSA-PSO algorithm in MATLAB® code is linked to finite-difference time-domain solution technique based on Lumerical-software to simulate and optimize the Si NWs’ geometrical parameters. The suggested GSA-PSO algorithm has advantages in terms of better convergence and final fitness values than that of the PSO algorithm. Further, the Si NWs lattice with optimized diameters and heights shows a high ultimate efficiency of 42.5% with an improvement of 42.8% over the Si NWs lattice with the same diameters and heights. This enhancement is attributed to the different generated optical modes combined with multiple scattering and reduced reflection due to the different heights and different diameters, respectively.
A design of a transverse electric (TE)-pass polarizer based on hybrid plasmonic silicon-on-insulator (SOI) platform is reported and analyzed using full vectorial finite element method. The proposed design has gold nanorods that are injected into the silicon dioxide substrate to tolerate the function of the device, and hence the required polarizing state can be obtained. Detailed design principle is presented, taking advantage of the distinct confinements of the TE and transverse magnetic modes in the core region and their coupling with the surface plasmon modes around the metallic nanorods. According to the positions of the gold nanorods, the suggested plasmonic SOI can be used as a TE-pass polarizer with a compact device length of 1.85 μm with 0.1639 dB insertion losses and extinction ratio of 14.58 dB at wavelength of 1.55 μm. The optimized geometrical parameters offer 3 orders of magnitude smaller than similar devices previously demonstrated on the SOI platform. The proposed design has advantages in terms of simplicity and compactness, which makes it a good candidate to be used in integrated silicon photonics. Further, the compact device size and good performance could provide a simple yet satisfactory solution to the polarization-dependent performance drawback of the silicon photonics devices on the SOI platform.
A design of a highly sensitive multichannel biosensor based on photonic crystal fiber is proposed and analyzed. The suggested design has a silver layer as a plasmonic material coated by a gold layer to protect silver oxidation. The reported sensor is based on detection using the quasi transverse electric (TE) and quasi transverse magnetic (TM) modes, which offers the possibility of multichannel/multianalyte sensing. The numerical results are obtained using a finite element method with perfect matched layer boundary conditions. The sensor geometrical parameters are optimized to achieve high sensitivity for the two polarized modes. High-refractive index sensitivity of about 4750 nm/RIU (refractive index unit) and 4300 nm/RIU with corresponding resolutions of 2.1×10−5 RIU, and 2.33×10−5 RIU can be obtained according to the quasi TM and quasi TE modes of the proposed sensor, respectively. Further, the reported design can be used as a self-calibration biosensor within an unknown analyte refractive index ranging from 1.33 to 1.35 with high linearity and high accuracy. Moreover, the suggested biosensor has advantages in terms of compactness and better integration of microfluidics setup, waveguide, and metallic layers into a single structure.
In this paper, a novel design of hybrid silicon plasmonic transverse electric (TE) pass polarizer based on silicon-oninsulator (SOI) platform is reported and analyzed. The numerical results are obtained by using full vectorial finite element method. The suggested design depends on gold rods that are injected into the substrate in order to tolerate the function of the device and hence the required polarizing state can be obtained. The proposed SOI TE polarizer can achieve -0.19 dB insertion losses with compact device length of 18 μm. Further, the introduced device is easy for fabrication and is compatible with the standard CMOS fabrication process.
In this paper, a novel design of highly sensitive biosensor based on photonic crystal fiber is presented and analyzed using full vectorial finite element method. The suggested design depends on using silver layer as a plasmonic active material coated by a gold layer to protect silver oxidation. The reported sensor is based on the detection using the quasi transverse electric (TE) and quasi transverse magnetic (TM) modes which offers the possibility of multi-channel/multi-analyte sensing. The sensor geometrical parameters are optimized to achieve high sensitivity for the two polarized modes. High refractive index sensitivity of about 4750 nm/RIU (refractive index unit) and 4300 nm/RIU with corresponding resolutions of 2.1×10-5 RIU, and 2.33×10-5 RIU can be obtained for the quasi TM and quasi TE modes, respectively.
Silicon nanowires (SiNWs) are the subject of intense research in solar energy harvesting due to their unique electrical and optical characteristics. The transmission, reflection, and absorption spectra of decagonal Si NWs (D-SiNWs) solar cells have been calculated using a three-dimensional finite-difference time-domain method to present a design guideline for ultra-high efficiency SiNW in solar cell applications. In this study, the structure geometrical parameters of the suggested design are tuned to maximize light absorption. The ultimate efficiency is used to quantify the absorption enhancement of the SiNWs solar cells. A maximum ultimate efficiency of 39.3% is achieved for the reported D-SiNWs, which is greater than that of the previous work of slanting Si NWs by 17.49%.
A photonic crystal fiber (PCF) surface plasmon resonance (SPR) based sensor is proposed and analysed. The proposed sensor consists of microuidic slots enclosing a dodecagonal layer of air holes cladding and a central air hole. The sensor can perform analyte detection using both HEx 11 and HEy 11 modes with a relatively high sensitivities up to 4000 nm=RIU and 3000 nm=RIU and resolutions of 2.5×10-5 RIU-1 and 3.33×10-5 RIU-1 with HEx11 and HEy11, respectively, with regards to spectral interrogation which to our knowledge are higher than those reported in the literature. Moreover, the structure of the suggested sensor is simple with no fabrication complexities which makes it easy to fabricate with standard PCF fabrication technologies.
In this paper, compact three trenched channel plasmonic microring resonator sensor (TTCP-MRRS) on a silicon-oninsulator substrate is proposed and analyzed. The three trenched waveguide is composed of three metal-gaps-silicon structure, where the optical energy is greatly enhanced in the narrow gaps. The full vectorial finite element method is used to numerically analyze the device optical characteristics as a biochemical sensor. As the optical field in the proposed structure has a large overlap with the upper-cladding sensing medium, the sensitivity is very high compared to other dielectric microring resonator sensors. The sensitivity is the ratio between the resonance wavelength shift and the cladding refractive index change, which is a key parameter to describe the sensor performance. The detection limit (DL), which is defined as the minimum refractive index change in the sensing medium that can be detected by the sensor system, is proportional to the resonance line width Δλ or inversely proportional to the resonance Q-factor. So, in order to properly evaluate the sensing performance of the proposed channel plasmonic microring resonator sensor, a figure of merit (FOM) can be defined as the number of resonance line width shift in response to a unit cladding refractive index change. The proposed (TTCP-MRRS) has a compact size and high sensitivity and can be integrated in an array form on a chip for highly-efficient lab-on-chip biochemical sensing applications.
In this paper, a novel design of tellurite photonic crystal fiber (PCF) is presented and analyzed. The proposed design is analyzed using full-vectorial finite-difference method (FVFDM). The analyzed parameters are the birefringence, effective mode area, nonlinearity and dispersion for the two fundamental polarized modes. The effects of the structure geometrical parameters on the modal properties are studied in detail. The numerical analysis reveals that the proposed design has high birefringence of 0.10568 and high nonlinearity of 4784 W-1 Km-1 and 4030 W-1 Km-1 for the quasi transverse magnetic (TM) and quasi transverse electric (TE) modes, respectively at the operating wavelength of 1.55 μm with low losses for the two fundamental polarized modes. Also, the dispersion of the reported design can be tailored to achieve flat and zero dispersion at the desired wavelength.